[Clinical value of gastrointestinal bleeding scintigraphy in vivo using 99mTc-labeled erythrocytes].

99mTc labeled red blood cell imaging was performed in 13 patients with clinical evidence of gastrointestinal bleeding from an unknown source. In all these patients the bleeding sites had remained unclear after the standard diagnostic evaluation, including upper gastrointestinal endoscopy (13 patients), colonoscopy (12 patients) and angiography (4 patients). Nine of 13 patients (70%) had a scan indicating active bleeding. In the 10 patients in whom the bleeding site was definitely identified by endoscopy, arteriography, or surgery, scintigraphy correctly localized the bleeding site in 6 (60%). One false positive localization was noted. Bleeding was detected in 7 of 9 patients with melena and in 2 of 4 patients with occult bleeding and chronic anemia. In all but 1 patient, additional diagnostic investigations were needed to finally establish the bleeding site. In patients in whom a potential bleeding site has been identified by standard diagnostic tests, 99mTc red blood cell imaging may provide a reliable noninvasive test by which to document active bleeding from the suspected source.